Jake uses a fire extinguisher to put out a small fire. When he squeezes the handle, the flame retardant is released from the extinguisher with considerable force. As a result, Jake has to reinforce his grip on the extinguisher to hold it in place as it pushes back into his hands. The projectile in this scenario is the . The recoil in this scenario is the . The force on the flame retardant is the force on the extinguisher. The mass of the flame retardant is the mass of the extinguisher. The acceleration of the flame retardant is the acceleration of the extinguisher.